#include <fcntl.h>
#include <gio/gio.h>
#include <gio/gunixfdlist.h>
#include <inttypes.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <webkit2/webkit-web-extension.h>
#include <webkitdom/WebKitDOMDOMWindowUnstable.h>
#include <webkitdom/webkitdom.h>

#define MSGBUFSZ 8

#define LENGTH(x) (sizeof(x) / sizeof(x[0]))

static WebKitWebExtension *webext;
static int sock;

/*
 * Return:
 * 0 No data processed: need more data
 * > 0 Amount of data processed or discarded
 */
static size_t evalmsg(char *msg, size_t sz) {
  char js[48];
  WebKitWebPage *page;
  JSCContext *jsc;
  JSCValue *jsv;

  if (!(page = webkit_web_extension_get_page(webext, msg[0]))) {
    return sz;
  }

  if (sz < 2) {
    return 0;
  }

  jsc = webkit_frame_get_js_context(webkit_web_page_get_main_frame(page));
  jsv = NULL;

  switch (msg[1]) {
  case 'h':
    if (sz < 3) {
      sz = 0;
      break;
    }
    sz = 3;
    snprintf(js, sizeof(js), "window.scrollBy(window.innerWidth/100*%hhd,0);",
             msg[2]);
    jsv = jsc_context_evaluate(jsc, js, -1);
    break;
  case 'v':
    if (sz < 3) {
      sz = 0;
      break;
    }
    sz = 3;
    snprintf(js, sizeof(js), "window.scrollBy(0,window.innerHeight/100*%hhd);",
             msg[2]);
    jsv = jsc_context_evaluate(jsc, js, -1);
    break;
  default:
    fprintf(stderr, "%s:%d:evalmsg: unknown cmd(%zu): '%#x'\n", __FILE__,
            __LINE__, sz, msg[1]);
  }

  g_object_unref(jsc);
  if (jsv) {
    g_object_unref(jsv);
  }

  return sz;
}

static gboolean readsock(GIOChannel *s, GIOCondition c, gpointer unused) {
  static char msg[MSGBUFSZ];
  static size_t msgoff;
  GError *gerr = NULL;
  size_t sz;
  gsize rsz;

  if (g_io_channel_read_chars(s, msg + msgoff, sizeof(msg) - msgoff, &rsz,
                              &gerr) != G_IO_STATUS_NORMAL) {
    if (gerr) {
      fprintf(stderr, "webext: error reading socket: %s\n", gerr->message);
      g_error_free(gerr);
    }
    return TRUE;
  }
  if (msgoff >= sizeof(msg)) {
    fprintf(stderr, "%s:%d:%s: msgoff: %zu", __FILE__, __LINE__, __func__,
            msgoff);
    return FALSE;
  }

  for (rsz += msgoff; rsz; rsz -= sz) {
    sz = evalmsg(msg, rsz);
    if (sz == 0) {
      /* need more data */
      break;
    }
    if (sz != rsz) {
      /* continue processing message */
      memmove(msg, msg + sz, rsz - sz);
    }
  }
  msgoff = rsz;

  return TRUE;
}

static void pageusermessagereply(GObject *o, GAsyncResult *r, gpointer page) {
  WebKitUserMessage *m;
  GUnixFDList *gfd;
  GIOChannel *gchansock;
  char const *name;
  int nfd;

  m = static_cast<WebKitUserMessage *>(
      webkit_web_page_send_message_to_view_finish(
          static_cast<WebKitWebPage *>(page), r, NULL));
  name = webkit_user_message_get_name(m);
  if (strcmp(name, "surf-pipe") != 0) {
    fprintf(stderr, "webext-surf: Unknown User Reply: %s\n", name);
    return;
  }

  gfd = webkit_user_message_get_fd_list(m);
  if ((nfd = g_unix_fd_list_get_length(gfd)) != 1) {
    fprintf(stderr, "webext-surf: Too many file-descriptors: %d\n", nfd);
    return;
  }

  sock = g_unix_fd_list_get(gfd, 0, NULL);

  gchansock = g_io_channel_unix_new(sock);
  g_io_channel_set_encoding(gchansock, NULL, NULL);
  g_io_channel_set_flags(
      gchansock,
      static_cast<GIOFlags>(g_io_channel_get_flags(gchansock) |
                            G_IO_FLAG_NONBLOCK),
      NULL);
  g_io_channel_set_close_on_unref(gchansock, TRUE);
  g_io_add_watch(gchansock, G_IO_IN, readsock, NULL);
}

void pagecreated(WebKitWebExtension *e, WebKitWebPage *p, gpointer unused) {
  WebKitUserMessage *msg;

  msg = webkit_user_message_new("page-created", NULL);
  webkit_web_page_send_message_to_view(p, msg, NULL, pageusermessagereply, p);
}

G_MODULE_EXPORT void webkit_web_extension_initialize(WebKitWebExtension *e) {
  webext = e;

  g_signal_connect(G_OBJECT(e), "page-created", G_CALLBACK(pagecreated), NULL);
}
